Dejan Petrovic

Synthesis and reactivity of copper(I) complexes containing a bis(imidazolin-2-imine) pincer ligand

The new pincer ligand 2,6-bis[(1,3-di-tert-butylimidazolin-2-imino)methyl]pyridine (TL(tBu)) has been prepared in high yield from 2,6-bis(hydroxymethyl)pyridine (1) and 1,3-di-tert-butylimidazolin-2-imine (3). Reaction of TL(tBu) with [Cu(MeCN)4]PF6 affords the highly reactive copper(I) complex [(TL(tBu))Cu]PF6, [5]PF6, which forms the stable copper(I) isocyanide complexes [6a]PF6 (nu(CN) = 2179 cm(-1)) and [6b]PF6 (nu(CN) = 2140 cm(-1)) upon addition of tert-butyl or 2,6-dimethylphenyl isocyanide, respectively. For the cations 6a and 6b, DFT calculations reveal ground-state electronic structures of the type [(TL(tBu)-kappaN(1):kappaN(2))Cu(CNR)] with tricoordinate geometries around the copper atoms. Exposure of [5]PF6 to the air readily leads to trapping of atmospheric CO2 to form the square-planar complex [(TL(tBu))Cu(HCO3-kappaO)]PF6, [7]PF6, with the bicarbonate ligand adopting a rarely observed monodentate coordination mode. In chlorinated solvents such as dichloromethane or chloroform, [5]PF(6) rapidly abstracts chloride by reductive dechlorination of the solvent to yield [(TL(tBu))CuCl]PF6, [8]PF6 quantitatively. Reaction of TL(tBu) with copper(I) bromide or chloride affords complexes 9a and 9b, respectively, for which X-ray diffraction analysis, low-temperature NMR experiments and DFT calculations reveal the presence of a kappa(2)-coordinated ligand of the type [(TL(tBu)-kappaN(1):kappaN(2))CuX]. In solution, complex 9b undergoes slow disproportionation forming the mixed-valence copper(II)/copper(I) system [(TL(tBu))CuCl][CuCl2], [8]CuCl2 with a linear dichlorocuprate(I) counterion.

Strong hydrogen bonds in the ionic pair (1,3-diisopropyl-4,5-dimethyl-4-imidazolin-2-ylidene)ammonium trichloro(1,3-diisopropyl-4,5-dimethyl-4-imidazolin-2-ylideneamine)iron(II).

The title compound, (C11H22N3)[FeCl3(C11H21N3)], is one of the rare examples where an isolated ionic pair of the type [A]n+ [EMX3]n- (E is any non-metal, M is any transition metal and X is any halogen) could be structurally characterized. Two short N-H...Cl contacts between the two ammonium H atoms and two of the three Cl atoms of the counter-anion generate a six-membered ring. The third Cl atom is involved in a weaker intramolecular hydrogen bond to the neutral 1,3-diisopropyl-4,5-dimethyl-4-imidazolin-2-ylideneamine ligand.

Structural Characterization of Cationic 16-Electron Pentamethylcyclopentadienyl Ruthenium(II) Complexes Containing the Binuclear [Cp*Ru(μ-Cl)3RuCp*]– Anion

Abstract The reaction of the diimine ligand 1,2-bis(1,3-diisopropyl-4,5-dimethylimidazolin-2-imino)ethane (BLiPr) with tetrameric [Cp*RuCl]4 in a 1 : 0.75 ratio afforded the complex salt [1][2] containing the 16-electron half-sandwich cation [Cp*Ru(BLiPr)]+ (1) and the dinuclear anion [Cp*Ru(μ- Cl)3RuCp*]− (2). The X-ray crystal structures of [1][2]·31/2THF (monoclinic, space group P21/n, Z = 4) and of [1][2]·THF (monoclinic, space group C2/m, Z = 4) are reported, allowing the structural characterization of the unprecedented anion 2, in which two [(η5-C5Me5)Ru(II)] moieties are bridged by three μ2-chlorine atoms.

A solvent‐free modification of {2,6‐bis[(1,3‐di‐tert‐butylimidazolin‐2‐ylideneamino)methyl]pyridine}(hydrogen carbonato)copper(II) hexafluoridophosphate

A new crystal form of the title compound, [Cu(CHO3)(C29H47N7)]PF6, is closely similar in cation geometry to the previously reported acetone solvate [Petrovic, Bannenberg, Randoll, Jones & Tamm (2007). Dalton Trans. pp. 2812–2822]. The coordination at the Cu atom is square planar, although the O atom lies 0.224 (5) A out of the N3 ligand plane. The cations are associated to form inversion-symmetric dimers via hydrogen bonding between bicarbonate units.